Levels of first winter feeding in relation to performance of Cheviot hill ewes: VI. Life-time production form the hill

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Abstract
SUMMARY The effects of different levels of first-winter nutrition over 3 years were studied on the subsequent life-time production from the hill of groups of North and South Country Cheviot ewe hoggs (sheep between 6 months and 1½12 years). Lamb production was examined in terms of the percentage of lambs born and reared per ewe alive at each lambing and was expressed as a mean of five lamb crops. An overall measure of flock life-time production was calculated from the data on lamb production. This was the total number of lambs weaned at a mean 15 weeks in each treatment group over five lamb crops expressed as the mean per experimental animal alive at 6 months. All productive components were analysed for differences between breeds, treatments, and weight-classes, i.e. those animals above or below average weight at 6 months. There were no significant treatment differences in life-time production, although the treatment groups showed different trends with increasing age. Higher production in early life following higher levels of first-winter nutrition was associated with less efficient later production and poorer ewe survival in a hard hill environment. It is concluded that improvement in first-winter nutrition above that available on the hill is undesirable and uneconomic without equal improvement in adult nutrition.